1. Field of the Invention
The present invention relates generally to computer-aided design software, and in particular, to a method, system, apparatus, computer program product, and article of manufacture for sweeping a profile along small circular arcs.
2. Description of the Related Art
Computer-aided design (CAD) users often use a sweep operation to cut model edges with any profile that they want. However, all modeling programs in the design software industry disallow a large profile to be swept around small circular arcs of a path. As the profile is swept around the axis of an arc with a radius smaller than the profile size, the profile crosses the axis. This situation causes self-intersecting geometry around the circular path segment, so the sweep operation fails. In reality, it is possible to physically create the shape with machining tools, such as a half round mill or cutter. In other words, in reality, it may be easier to create geometry by manufacturing/milling than it is to model the same geometry. Since more and more manufacturing is driven from solid modeling output, the ability to easily create manufacturable output is a factor in improved customer satisfaction and competitive differentiation. Accordingly, it is desirable to enable design software to be able to sweep a profile (e.g., a large profile) along small circular arcs of a path to create a valid sweep result.
FIGS. 1-5 illustrate the prior art problems associated with creating illegal geometry. FIG. 1 illustrates an object 100 to be swept using a profile 102 along path 104. FIG. 2 illustrates the outline 202 of the resulting shape after sweeping profile 102 along path 104. FIG. 3 illustrates the position of the profile 102A prior to sweeping the profile 102 along the circular arc 104A of path 104. FIG. 4 illustrates the rotation 402 around the axis of rotation 404 of the profile 102 as the sweep operation proceeds around the circular arc of path 104. Once the sweep around arc 104A is completed, the outline of the shape along circular path 104A is illustrated at 406. FIG. 5 illustrates different angles of the resulting illegal geometry 406 that are not allowed. As a consequence of the resulting illegal geometry, when produced, prior art systems often exit and/or produce errors such that the sweep operation cannot be conducted or is resolved unacceptably.
In view of the above, what is needed is the capability to methodically and correctly conduct a valid sweep operation of a profile along a circular arc of a path (that results in a valid object).